JP2001152088A - Cationic electrodeposition coating composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide electrodeposition coating film that shows low heating loss, excellent low-temperature curing properties and high smoothness. SOLUTION: In a block polyisocyanate curing type cationic electrodeposition coating composition, this coating composition characteristically includes blocked polyisoyanate groups, as a crosslinking agent, represented by general formula (2) (A is an isocyanine residual group and R1 is H, methyl, ethyl or propyl; R2 is methyl or ethyl), blocked with an amide represented by general formula (1): R1-CO-NH-R2 [wherein R1 and R2 are each the same meaning as stated in general formula (2)] as a crosslinking group.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrodeposition coating composition, and more particularly to an electrodeposition coating composition containing a blocked polyisocyanate cross-linking agent. The present invention relates to a cationic electrodeposition coating composition capable of forming an electrodeposition coating film having good smoothness.

[0002]

2. Description of the Related Art Blocked polyisocyanate compounds used as a cross-linking agent in a cationic electrodeposition coating composition obtained by reacting an amine-added epoxy resin with a blocked polyisocyanate and heat curing include polyisocyanate. Compounds and blocking agents are included. As the polyisocyanate compound,
For example, aromatic, alicyclic, and aliphatic such as tolylene diisocyanate, xylylene diisocyanate, bis (isocyanatomethyl) cyclohexane, tetramethylene diisocyanate, hexamethylene diisocyanate, methylene diisocyanate, isophorone diisocyanate, phenylene diisocyanate, and diphenyl diisocyanate. Of polyisocyanate compounds.

[0003] On the other hand, a blocking agent is one that blocks by adding to an isocyanate group of a polyisocyanate compound, and the blocked isocyanate compound formed by the addition is stable at ordinary temperature and usually about 10%.
It is important that the blocking agent can dissociate and regenerate free isocyanate groups when heated to a temperature in the range of 0 to about 200 ° C. Examples of the blocking agent satisfying such requirements include ε-caprolactam and γ-caprolactam.
Lactam compounds such as butyrolactam; oxime compounds such as methyl ethyl ketoxime and cyclohexanone oxime; phenol, para-t-butylphenol;
Phenolic compounds such as cresol; aliphatic alcohols such as n-butanol and 2-ethylhexanol; aromatic alkyl alcohols such as phenylcarbinol and methylphenylcarbinol; ether alcohol compounds such as ethylene glycol monobutyl ether; No.

Conventionally, aromatic or aliphatic polyisocyanates and ether alcohol-based compounds have been used as polyisocyanates in view of the anticorrosion properties of coatings and the stability of coatings. However, low-temperature curability of the coating film is required due to an increase in the amount of dirt and soot in the line dryer due to the weight loss due to heating (the weight loss ratio during baking and curing of the coating film) and the cost reduction due to the decrease in the baking temperature of the line dryer. An oxime compound was effective as a blocking agent.

However, when an aromatic or aliphatic system is used as the polyisocyanate and an oxime system is used as the blocking agent, the coating has problems with time stability and anticorrosion, and has anticorrosion and stability of the coating. There has been a demand for the development of a crosslinking agent in an electrodeposition coating composition for obtaining low heat loss and low-temperature curability.

[0006]

Means for Solving the Problems The present inventors diligently studied to solve the above problems. As a result, in the block polyisocyanate-curable cationic electrodeposition as a cross-linking agent in the electrodeposition coating composition, the use of a specific cross-linking agent as a cross-linking agent also provides excellent anticorrosion properties and stability, and improves the above-mentioned problems. And completed the present invention.

That is, the present invention provides: In the blocked polyisocyanate-curable cationic electrodeposition coating composition, at least one isocyanate group per molecule as a cross-linking agent is represented by the general formula (1): R ₁ —CO—NH—R ₂ (1) (where R ₁ is A hydrogen atom, a methyl group, an ethyl group or a propyl group, and R ₂ represents a methyl group or an ethyl group.)

[0008]

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(Wherein, A represents an isocyanate compound residue, and R ₁ and R ₂ have the same meanings as described above). In the cationic electrodeposition coating composition and the block polyisocyanate-curable cationic electrodeposition coating, the resin used in the coating has an average of 0.1 or more groups represented by the general formula (2) bonded thereto. 2. A cationic electrodeposition coating composition, which is a resin for a cationic electrodeposition coating composition containing a blocked isocyanate group. 3. a cationic electrodeposition coating composition wherein the polyisocyanate compound is an aromatic polyisocyanate; The amide compound according to claim 1 or 2, wherein the amide compound is at least one compound selected from n-methylacetamide, n-ethylacetamide, n-methylpropylamide, and n-methylformamide. 4. a coating composition, In the above cationic electrodeposition coating composition, the bismuth content of the inorganic bismuth compound and / or the organic acid bismuth salt is adjusted to 0.01 to 10 parts by weight based on 100 parts by weight of the resin solid content in the electrodeposition coating composition. The above 1-4 to mix
The cationic electrodeposition coating composition according to any one of the above items,

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The cationic electrodeposition coating composition of the present invention is a cationic electrodeposition coating composition in which a cationic base resin containing active hydrogen that reacts with isocyanate groups is cured by heating with blocked polyisocyanate groups.

The blocked polyisocyanate may be blended with an active hydrogen group-containing cationic base resin as an external crosslinking agent (coating composition A according to claim 1) or may be used as an active hydrogen group-containing cationic base resin. It may be contained as an internal crosslinking agent bonded to the resin (the coating composition B according to claim 2).

The coating composition A is described below.
As the base resin, any resin such as an epoxy resin, an acrylic resin, a polybutadiene resin, an alkyd resin, and a polyester resin can be used, but an epoxy resin is preferable, and an amine is added to the resin to form a cationic electrodeposition coating composition. Used as

Examples of the amine-added epoxy resin include, for example, adducts of (I) polyepoxy compounds with primary mono- and polyamines, secondary mono- and polyamines, or primary and secondary mixed polyamines (for example, US Pat. (II) polyepoxide compounds and adducts of polyepoxide compounds with ketiminated secondary mono- and polyamines having primary amino groups (see, for example, U.S. Pat. No. 4,017,438); (III) polyepoxides A reaction product obtained by etherification of a compound with a ketiminated hydroxy compound having a primary amino group (for example, JP-A-59-43013)
Reference) can be cited.

The polyepoxide compound used for producing the amine-added epoxy resin is a compound having two or more epoxy groups in one molecule, and generally has at least 20 epoxy groups.
0, preferably 400-4000, more preferably 80
Those having a number average molecular weight in the range of 0 to 2,000 are suitable, and particularly those obtained by reacting a polyphenol compound with epichlorohydrin are preferable. Examples of the polyphenol compound that can be used for forming the polyepoxide compound include bis (4-hydroxyphenyl) -2,2-propane, 4,4-dihydroxybenzophenone, and bis (4-hydroxyphenyl) -1,1.
-Ethane, bis (4-hydroxyphenyl) -1,1-
Isobutane, bis (4-hydroxy-tert-butyl-phenyl) -2,2-propane, bis (2-hydroxynaphthyl) methane, tetra (4-hydroxyphenyl)-
Examples thereof include 1,1,2,2-ethane, 4,4-dihydroxydiphenylsulfone, phenol novolak, and cresol novolak.

The polyepoxide compound is a polyol,
Polyether polyol, polyester polyol, polyamidoamine, polycarboxylic acid, may be partially reacted with a polyisocyanate compound and the like, furthermore, ε-caprolactone, and those obtained by graft polymerization of acrylic monomers, etc. Is also good. Examples of the blocked polyisocyanate used as a crosslinking agent for the coating composition A include, for example, tolylene diisocyanate, xylylene diisocyanate, phenylene diisocyanate, bis (isocyanatomethyl) cyclohexane, tetramethylene diisocyanate, hexamethylene diisocyanate, methylene diisocyanate, and isophorone diisocyanate. Aromatic, aliphatic or alicyclic polyisocyanate compounds, and an excess amount of these isocyanate compounds are reacted with a low-molecular-weight active hydrogen-containing compound such as ethylene glycol, propylene glycol, trimethylolpropane, hexanetriol, or castor oil. Is obtained by reacting the terminal isocyanate-containing compound thus obtained with the amide compound represented by the general formula (1).

Among them, aromatic diisocyanates, especially diphenylmethane-2,4'-diisocyanate, diphenylmethane-4,4'-diisocyanate (commonly called MDI), and diphenylmethane-
4,4'-diisocyanate and diphenylmethane-2,
Polyisocyanate compounds such as a mixture of 4'-diisocyanate and polymethylene polyphenylisocyanate (usually called crude MDI) are preferred.

The blocking agent is one that blocks by adding to the isocyanate group of the polyisocyanate compound, and the blocked polyisocyanate compound formed by the addition is stable at room temperature and is about 100 to 20.
When heated to 0 ° C, preferably 120 to 150 ° C, it is desirable that the blocking agent be dissociated to regenerate free isocyanate groups. Also, as the molecular weight of the dissociating blocking agent is smaller, the formed heating loss is smaller,
In addition, this contributes to low drying and soot in the drying furnace.

Examples of such a blocking agent include low molecular polyamides, and particularly preferred are amides such as n-methylacetamide, n-ethylacetamide, n-methylpropionamide and n-methylformamide. It may be used alone or in combination. Some of the blocks used conventionally may be used in combination. As such a blocking agent, for example, ε-
Lactam compounds such as caprolactam and γ-butyrolactam; oxime compounds such as methyl ethyl ketoxime and cyclohexanone oxime; phenol, para-
Phenolic compounds such as t-butylphenol and cresol; aliphatic alcohols such as n-butanol and 2-ethylhexanol; aromatic alkyl alcohols such as phenylcarbinol and methylphenylcarbinol; ether alcohols such as ethylene glycol monobutyl ether And the like.

The amount of the blocking agent is preferably 1: 1 to 1: 1.3 with respect to the NCO group of the isocyanate. If the ratio exceeds 1.3, the blocking agent remains to lower the corrosion resistance of the coating film, and if the ratio is less than 1.0, NCO groups remain to impair the stability of the coating composition, which is not preferable.

In the blocked polyisocyanate,
Diphenylmethane-4,4'-diisocyanate (MD
Taking I) as an example, the following structure is obtained.

[0021]

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(Wherein R ₁ represents a hydrogen atom, a methyl group, an ethyl group or a propyl group, R ₂ represents a methyl group or an ethyl group, and A represents a residue of an isocyanate compound). -Water-solubilization is usually carried out by neutralizing the resin with an aliphatic carboxylic acid, particularly a water-soluble organic acid such as acetic acid and / or formic acid, and solubilizing and dispersing in water. It is preferable to use acetic acid and / or formic acid as the neutralizing agent because they are excellent in finishing properties, throwing power, low-temperature curability, and the like.

Next, the coating composition B will be described. The coating composition B is a block polyisocyanate-curable cationic electrodeposition coating composition. The resin used in the coating composition is a blocked polyisocyanate formed by bonding an average of 0.1 or more groups represented by the general formula (2). It is a resin for a cationic electrodeposition coating composition containing an isocyanate group and a cationic group. The coating resin is, for example, half-blocked with a base resin containing an active hydrogen group (primary or secondary amino group or hydroxyl group (in the epoxy resin)) obtained by reacting an epoxy resin with a polyamine compound. It is obtained by reacting with a polyisocyanate compound. The resin comprises a blocked polyisocyanate component and a cationic group (amino group,
Crosslinked cationic base resin containing a quaternary amino group). It is preferable that the resin has an average of 0.1 or more, preferably 0.2 to 1.2 groups represented by the general formula (2) in the resin. If the number is less than 0.1, the crosslink density decreases and the corrosion resistance deteriorates.

In general, the coating composition B is neutralized and made water-soluble by neutralizing the resin with an aliphatic carboxylic acid, in particular, a water-soluble organic acid such as acetic acid and / or formic acid. Done by It is preferable to use acetic acid and / or formic acid as the neutralizing agent because they are excellent in finishing properties, throwing power, low-temperature curability, and the like.

As a method for producing a resin in which the half-blocked polyisocyanate compound is added to the base resin, for example, the amine-added epoxy resin described in the coating composition A and the free isocyanate group of the partially blocked crosslinking agent are used. It is obtained by reacting until it is substantially eliminated (it can be confirmed by analysis in an infrared absorption spectrum). The partially blocked cross-linking agent converts the MDI into an inert organic solvent (eg, an ester solvent, a ketone solvent, or the like) that does not substantially react with the MDI and the amide compound as required.
Aromatic solvents, ether solvents, etc.)
For example, it can be obtained by reacting at about 20 to 150 ° C, preferably 30 to 100 ° C, for about 10 minutes to 24 hours, preferably for about 20 minutes to 15 hours. The mixing ratio of MDI and a blocking agent containing an amide compound is about 1.0 to 1.98 moles, preferably about 1.05 to 1.98 moles per mole of MDI.
It is in the range of 1.95 mol.

A schematic diagram of a resin obtained by adding the half-blocked polyisocyanate compound to a base resin is shown below.

[0027]

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(In the formula, A, R ₁ and R ₂ have the same meanings as described above.) The electrodeposition coating composition of the present invention may further contain a tin compound. Examples of the tin compound include organic tin oxides such as dibutyltin oxide and dioctyltin oxide; dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin diacetate, dioctyltin benzoateoxy, dibutyltin benzoateoxy, dioctyltin dibenzoate, Examples thereof include fatty acids or aromatic carboxylate salts of dialkyltin such as dibutyltin dibenzoate. Of these, dialkyltin aromatic carboxylate salts are preferred from the viewpoint of low-temperature curability.

The content of the tin compound in the electrodeposition coating composition is not strictly defined, and can be varied over a wide range according to the performance required for the electrodeposition coating. The tin content per 100 parts by weight of the resin solid content in the coating material is 0 to 8 parts by weight, preferably 0.05 to 5 parts by weight.
It is preferred to be within the range of parts by weight.

The electrodeposition coating composition of the present invention may further contain, if necessary, coating additives such as a coloring pigment, an extender pigment, an organic solvent, a pigment dispersant, and a coating surface modifier.

The electrodeposition coating composition of the present invention can be applied to a desired substrate surface by electrodeposition coating. The electrodeposition coating is generally diluted with deionized water or the like so that the solid content concentration is about 5 to 40% by weight, and the pH is further adjusted to 5.5 to 5.5% by weight.
The electrodeposition bath comprising the electrodeposition coating composition of the present invention adjusted to the range of 9.0 can be usually adjusted to a bath temperature of 15 to 35 ° C. and a load voltage of 100 to 400 V.

The thickness of the electrodeposition coating film that can be formed using the electrodeposition coating composition of the present invention is not particularly limited,
Generally, the range is 10 to 40 μm, preferably 15 to 30 μm based on the dry coating film. The baking and curing temperature of the coating film is generally in the range of 100 to 200C, preferably in the range of 120 to 160C.

[0033]

According to the present invention, in a blocked polyisocyanate used as a cross-linking agent in an electrodeposition coating composition, a low-molecular weight amide compound is used as a blocking agent to achieve low heat loss and excellent low-temperature curability. A coating film is obtained.

[0034]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not limited by this. Note that “%” indicates “% by weight”.

Production Example 1 1010 g of Epicoat 828EL (trade name, epoxy resin, manufactured by Yuka Shell Co., Ltd.), 390 g of bisphenol A, and 0.2 g of dimethylbenzylamino were added and reacted at 130 ° C. until the epoxy equivalent reached 800. Next, 260 g of ε-caprolactone and 0.03 g of tetrabutoxytitanium were added, the temperature was raised to 170 ° C., sampling was performed over time while maintaining this temperature, and the amount of unreacted ε-caprolactone was traced in the infrared absorption spectrum measurement. , The reaction rate is 98
%, The temperature was lowered to 120 ° C. Next, 160 g of diethanolamine and 65 g of methyl isobutyl diketimine of diethylenetriamine were added,
For 4 hours, and add 420 g of butyl cellosolve,
Resin NO. Having an amine value of 58 and a resin solid content of 80%. 1 (plastic modified epoxy resin) was obtained.

Production Example 2 250 g of MDI and 40 g of methyl isobutyl ketone were added, and the temperature was raised to 70.degree. After slowly adding 110 g of methylacetamide, the temperature was raised to 90 ° C. By maintaining this temperature for 5 hours, the partially blocked crosslinking agent A having a solid content of 90% is obtained.
(MDI crosslinking agent (partially blocked isocyanate compound))
I got

Production Example 3 1010 g of Epicoat 828EL (trade name, epoxy resin, manufactured by Yuka Shell Co., Ltd.), 390 g of bisphenol A, and 0.2 g of dimethylbenzylamine were added and reacted at 130 ° C. until the epoxy equivalent reached 800. Next, 260 g of ε-caprolactone and 0.03 g of tetrabutoxytitanium
Was added, and the temperature was raised to 170 ° C. Sampling was conducted over time while maintaining this temperature, and the amount of unreacted ε-caprolactone was traced by measuring the infrared absorption spectrum. The temperature was lowered. Next, 399 g of the partially blocked crosslinking agent A prepared in Production Example 2 was added, and 1
Sampling was performed over time while maintaining the temperature at 00 ° C., and the reaction was performed until infrared absorption spectrometry confirmed that the absorption of unreacted isocyanate had disappeared. Next, 160 g of diethanolamine and 65 g of a ketimine compound of diethylenetriamine were added and reacted at 120 ° C. for 4 hours, 447 g of butyl cellosolve was added, and an amine value of 48 and a resin solid content of 8 were added.
0% resin NO. 2 (hardening agent-added plastically modified epoxy resin) was obtained.

Production Example 4 M-200 (trade name, Crude MDI, manufactured by Mitsui Chemicals, Inc.) 2
70 g and 46 g of methyl isobutyl ketone were added.
The temperature was raised to ° C. After slowly adding 146 g of methylacetamide, the temperature was raised to 90 ° C. Sampling was performed over time while maintaining this temperature, and by confirming that the absorption of unreacted isocyanate had disappeared by infrared absorption spectrum measurement, the crosslinking agent B (crude) having a solid content of 90% was obtained.
MDI crosslinking agent).

Production Example 5 M-200 (trade name, Crude MDI, manufactured by Mitsui Chemicals, Inc.) 2
70 g and 45 g of methyl isobutyl ketone were added, and the temperature was raised to 70 ° C. After slowly adding 73 g of methylacetamide and then 59 g of methylformamide, the temperature was raised to 90 ° C. While maintaining this temperature, sampling was conducted over time, and by confirming that the absorption of unreacted isocyanate had disappeared by infrared absorption spectrum measurement, the solid content was 90%.
% Crosslinker C (crude MDI crosslinker) was obtained.

Production Example 6 250 g of MDI and 44 g of methyl isobutyl ketone were added, and the temperature was raised to 70.degree. After slowly adding 146 g of methylacetamide, the temperature was raised to 90 ° C. While maintaining this temperature, sampling was conducted over time, and infrared absorption spectrum measurement confirmed that the absorption of unreacted isocyanate had disappeared.
[Diphenylmethane-4,4'-diisocyanate] crosslinking agent) was obtained.

Production Example 7 M-200 (trade name, Crude MDI, manufactured by Mitsui Chemicals, Inc.)
270 g and 92 g of methyl isobutyl ketone
The temperature was raised to ° C. After slowly adding 562 g of oleic acid amide, the temperature was raised to 90 ° C. While maintaining this temperature, sampling was performed over time, and infrared absorption spectrum measurement confirmed that the absorption of unreacted isocyanate had disappeared, thereby obtaining a crosslinking agent E (crude MDI crosslinking agent) having a solid content of 90%. .

Production Example 8 M-200 (trade name, Crude MDI, manufactured by Mitsui Chemicals, Inc.)
270 g and methyl isobutyl ketone 40 g
The temperature was raised to ° C. After slowly adding 92 g of ethanol, 9
The temperature was raised to 0 ° C. Sampling was performed over time while maintaining this temperature, and the absorption of unreacted isocyanate disappeared by infrared spectrum measurement, whereby a crosslinking agent F (crude MDI crosslinking agent) having a solid content of 90% was obtained.

Production of Clear Emulsion The resin NO. 187.5 g
(70 g resin solids), 33.3 g (30 g resin solids) of cross-linking agent A (crude MDI methylacetamide blocked product) obtained in Production Example 2, LSN-105
(Trade name, dibutyltin dibenzoate, solid content 40%, manufactured by Sankyoki Gosei Co., Ltd.) 2.5 g, 15 g of 10% acetic acid were blended, and the mixture was stirred uniformly. The resulting mixture was dropped over a period of minutes to obtain a clear emulsion a having a solids content of 34.0% for cationic electrodeposition. Similarly, in the combinations shown in Table 1, the emulsions b, c,
d, e, and f were obtained.

[0044]

[Table 1]

Preparation of Pigment Dispersion Paste 5.83 g of 60% quaternary chlorinated epoxy resin, titanium white
14.5 g, carbon black 0.4 g, extender pigment
7.0 g, lead silicate 2.0 g, deionized water 22.4 g
Was added to obtain a pigment-dispersed paste having a solid content of 55.0%.

Examples and Comparative Examples Example 1 A cationic electrodeposition emulsion a was added to 297 g.
49.8 g of pigment dispersion paste and 29 deionized water
5.2 g was added to obtain a cationic electrodeposition paint having a solid content of 20%.

Examples 2 to 5 and Comparative Examples 1 and 2 Each of the cationic electrodeposition emulsions b, c, d, e, and f, a pigment-dispersed paste and deionized water, were mixed in the same amounts as in Example 1. In addition, a cationic electrodeposition paint having a solid content of 20% was obtained.

Coating Test Each of the cationic electrodeposition paints obtained in the above Examples and Comparative Examples was subjected to a chemical conversion treatment with Palbond # 3020 (trade name, manufactured by Nippon Parkerazing Co., Ltd., zinc phosphate treating agent). 0.
An 8 × 150 × 70 mm cold-rolled dull steel plate was immersed and electrodeposited using this as a cathode. The baking was performed using an electric hot-air drier with an atmosphere temperature of two stages and a baking time of 20 minutes. Table 2 shows the performance test results of the obtained coated plates. The performance test was performed according to the following method.

[0049]

[Table 2]

(* 1) Heating loss After electrodeposition, preheating was performed at 105 ° C. for 3 hours. Thereafter, baking and drying are performed, and the ratio of weight loss is shown. The calculation was performed by the following formula. Weight of object to be coated Weight of coated plate after preheating Weight of coated plate after baking and drying ((-) / (-)) x 100 weight
% (* 2) Low-temperature curing property The coated surface of the electrodeposition coated plate obtained at each baking temperature is applied with a gauze of four layers soaked with acetone at a pressure of 3.92 mPa (about 4 kgf / cm ² ) for about 3 to 3 times.
The appearance of the coated surface after rubbing the length of 4 cm for 20 reciprocations was visually evaluated under the following conditions. ○ indicates no scratch on the painted surface, and △ indicates a scratch on the painted surface but the substrate is not visible. ×
For, the coating film dissolves and the substrate is visible.

(* 3) Corrosion resistance The coated plate obtained at each baking temperature was cross-cut with a knife to the electrodeposited coating so as to reach the substrate, and this was subjected to salt water resistance for 840 hours in accordance with JIS Z-2371. Spray test, scratch from knife wound,
The blister width was evaluated according to the following criteria. ○ indicates rust,
The maximum width of the blister is less than 2 mm from the cut (one side). △
Means that the maximum width of rust and blisters is at least 2 mm
mm (one side) and blisters are considerably conspicuous on the flat surface. × indicates that the maximum width of rust and blisters is 3 mm from the cut part
As described above, blisters are observed on the entire coated surface.

Claims (5)

[Claims] In a blocked polyisocyanate-curable cationic electrodeposition coating composition, at least one isocyanate group per molecule as a crosslinking agent has the general formula (1) R ₁ —CO—NH—R ₂ (1) , R ₁ represents a hydrogen atom, a methyl group, an ethyl group or a propyl group, and R ₂ represents a methyl group or an ethyl group.) The amide compound represented by the general formula (2) (Wherein A represents an isocyanate compound residue, and R ₁ and R
₂ has the same meaning as above. A cationic electrodeposition coating composition comprising a blocked polyisocyanate containing a group represented by the formula (I) as a crosslinking agent. 2. A blocked polyisocyanate-curable cationic electrodeposition paint, wherein the resin used in the paint is a blocked isocyanate comprising an average of 0.1 or more groups represented by the general formula (2) bonded to the resin. A cationic electrodeposition coating composition characterized by being a cationic electrodeposition coating resin containing a group. 3. The cationic electrodeposition coating composition according to claim 1, wherein the polyisocyanate compound according to claim 1 is an aromatic polyisocyanate. 4. The amide compound according to claim 1, wherein the amide compound is at least one compound selected from n-methylacetamide, n-ethylacetamide, n-methylpropylamide, and n-methylformamide. Cationic electrodeposition coating composition. 5. The cationic electrodeposition coating composition, wherein the bismuth content of the inorganic bismuth compound and / or the organic acid bismuth salt is 0.01 to 10 parts by weight based on 100 parts by weight of the resin solid content in the electrodeposition coating composition. The cationic electrodeposition coating composition according to any one of claims 1 to 4, wherein the cationic electrodeposition coating composition is blended so as to be a part.